Coupling for release at pre-determined load



J. 1.. DOUTT 3,344,487 COUPLING FQR RELEASE AT FIRE-DETERMINED LOADFiled April 2, 1965 :NvzN'r-oR Joseph L. DouH e ert inc'rllnadw Lift?"3,344,487 COUPLING FOR RELEASE AT PIKE-DETERMINED LOAD Joseph L. Doutt,Box 335, Wampum, Pa. 16157 Filed Apr. 2, 1965, Scr. No. 445,128

Claims. (Cl. 24-201) This invention relates to cogpli gg s fortransmitting ,rirr: w tcnsi e loads an'tl'WliiCfi are d signed to sepaate ata prg M. m s J jhescctu lina The invention is particularly usefulfci'fwater skiing and the like in which it is desired to have acouplingwhich will transmit a force adequate to tow the skier in normalposition, but which will release if an unexpected additional strain isplaced upon tfie tow rope.

7T tow ro e for water skiing ordinarily comprises a single line WlllChextends rearwardly from the boat to a point from which two lines divergeto opposite ends of a tow bar. The two lines diverging from that pointand the tow bar generally form a triangle when seen from above. Theskier holds the tow bar and is thereby pulled in a forward directionthrough the water.

Water skiing has become an increasingly more popular sport in recentyears. As the popularity of the sport has increased, it has also becomemore common to use boats having larger engines and to engage inacrobatics upon water skies. Such acrobatics, or stunt skiing, commonlyinvolve riding upon one ski or using one hand or one foot to hold thetow rope. At those times, water skiers frequently step over the tow ropewhile moving, as well as performing various jumps and changes ofposition.

In the course of stunt skiing, the chances of a spill or Sometimes theskier is upset and concurrently hasa hand urn not" 05v Hutu .1 nd. vare.

.or leg caught between the tow bar and one of the ropes.

The resistance offered by the skier in the water is, of I in a tow ropeby uncoupling the tow bar from the boat 3,344,487 Patented Oct. 3, 1 967springably embraced between the separated branches of thebifurcatedmember. In the preferred form of my invention, the' bifurcated member isformed of spring-like material and carries opposed non-planar pads orsurfaces at the ends of the separated sections. The second tensionmember, which is preferably in the form of a spool and.

has non-planar faces having a configuration disposed to .cooperate withthe non-planar faces upon the pads, is fitted between the pads and isspringably embraced between the arms of the bifurcated member. Ipreferably employ pads upon the ends of the bifurcated arms. which padshave convex surfaces. I further prefer that the spool member havecooperating concave faces which engage the convex faces. I

Other details, objects and advantages of my invention will become moreapparent as the following description of a present preferred embodimentthereof proceeds.

In the accompanying drawings, I have illustra'ted'a present preferredembodimentof my invention in which:

FIGURE 1 is a side view, taken in section, of a coupling embodying myinvention used in a water ski tow rope;

FIGURE 2 is a plan view, taken'in section, of the coupling illustratedin FIGURE 1;

FIGURE 3 is an end view of the coupling illustrated in FIGURE 1;

FIGURE 4 is a view of the opposite end of the coupling shown in FIGURE1; and

FIGURE 5 is a sectional view taken along line V--V of FIGURE 1.

The cou'gling includes-a gene ally lipdrical tube 1.

- Tube 1 is formed of several parts includinghfi'ifih'e'i' in e 2 and anouter tube 3. A tubular section 4 is preferahiv fitted between tubes 2and 3. Tubular member 4 is prefer ably of wood or some other buoyantmaterial and is sheathed in metal such as aluminum or the like toincrease the life of the coupling. Tubes 2 and 3, of course, constitutethe sheathing. The inner diameter of the entire cylindrical tube 1 isreduced to a smaller inside diameter at one end. I

A slidably movable rod 6 is fitted within the section 5 of smallerdiameter. One end of rod 6 has an enlarged before a dangerously hightension in the tow rope is reached.

I provide a body member having a recess or opening therein. I preferablyemploy a tubular body member having a bore therein. I further provide abifurcated member slidably positioned within the opening or recesswithin the body member, whereby varying lengths of thebranches of thebifurcated member may be positioned within the recess or projectingoutside the recess. I prefer to provide a cylindrical tube into whichthe bifurcated member is axially siidable. I further provide detentmeans operable between the body member and the bifurcated member to lockthem in desired relative position. I also prefer to provide a tensionmember adjustably positioned within the bore of the tubular member andconnected to the bifurcated member. The tension member is connected toone of the lines which is to be connected. The tension member ispreferably notched or grooved for reception of detent means therebyholding the bifurcated member in position. I further prefer to providestop I means adjustably positionedupon the tension member to limitsliding movement of the tension member and of the bifurcated member.

I further prefer to provide second tension members diameter or shoulder7 which is larger than the inner d1ameter of cylindrical tube -1 atsection 5. The shoulder section 7 is positioned .within the section oflarger diameter of cylindrical tube 1. Tube 1 is slidablc along rod 6.The other end 8 of rod 6 is external to tube 1. A bracket 9 is fastenedto end 8 of rod 6 by two screws 10. The central portion of rod 6 has anumber of circumferential grooves 11 formed within it. Inner sheathingtube 2 extends outwardly at the rod end of the coupling and has twocylindrical bores 12 within it. A coilspring 13 and a ball bearing 14are fitted within each of cylindrical bores 12. The springs 13 pressball bearings 14 into grooves 11.

Rod 6 is bored inwardly from its small end 8 forming a hole 15, intowhich a rope 16 is inserted. Rope 16 is locked into place within hole 15by screws or by knotting the end of the rope or the like. Any convenientmanner of fastening may readily be used. The fastening has not beenshown in further detail in the drawings to enablethe invention to beshown more clearly.

The end of rod 6 having shoulder 7 has a counterbore 17 drillc axiallyinto it. A pin 18 extends transversely through rod 6 and through thecounterbore. A bifurcated spring 19, which includes a loop 20, isinserted into the counterbore. Spring 19 di 'cs at its end remote fromloop 20 into a wish bone c having arms 21 and 22. By sliding tube 1 overred 6, the ends of arms 21 and 22 may be disposed within the bore oftube 1 or outside or" tube 1. A pad 23 is fastened to the inner end ofeach of arms 21 and 22 by a screw 24. A spool 25 is fitted between pads23. As will be seen from the drawings, the inwardly a? is.

ing arms 21 and 22. An eye 26 having an opening 27 is formed on one sideof spool 25. Spool 25 thereby transmits tension from a rope or the likethrough eye 26 to the rest of the coupling.

A thumb screw 28 is rotated into bracket 9 on an axis parallel to rod 6.Thumb screw 28 comes into contact. with the end of tube 1 and serves tolimit further movement of rod 6 into tube 1.

In use. till coupling is preferably laceg atlmw emf thetow rope and justaheadgj tl e tpgy bar in easy position to be reached bylhe water skier.Rod 6 is preferably connected to the rear end of the tow rope 16 and thetwo lines which connect to the ends of the tow bar preferably extendrearwardly from eye 26. Towing is customariiy commenced with the skierin the water. When the boat is started, there is a substantial draguntil the 2 "to thetime towing begins, thereby bringing shoulder 7 ofrod 6 against the section of reduced inner diameter 5 of tube 1. At thattime, arms 21 and 22 of spring 19 are completely contained withintube 1. It is impossiblefor them to spread apart and spool 25 is therebyfirmly locked between pads 23. After the skier has reached skiingposition, he slides tube '1 rearwardly over tube 6 until a desiredlength of arms 21 and 22 projects out of the end of tube 1. When theends of arms 21 and 22 do project out of tube 1, the application ofenough tension upon rope 16 and eye 25 will tend to cause spool 25 t bep lled from between pads 23, thereby forcing the ends of arms 21 and 22apart. When the tension exceeds some pre-determined amount, spool 25will be released, thereby permitting the boat to proceed without theskier. Such a-situation will occur if the skier falls into the water butcontinues to hold onto the towbar or becomes entangled in it.

It is, of course, apparent that skiers. of heavier weight will require agreater force for proper towing. Accordingly, the relative position ofrod 6 and tube 1 may be adjusted for skiers of different weights. Inlike fashion, acrobatic skiing may require more force than ordinarytowing. The greater the length of spring 19 which projects out of tube1, the less force will be required to separate the pads 23. Accordingly,rod 6 is adjusted relative to tube 1 until ball bearings 14 are in thedesired groove 11 to provide just enough force for proper towing withoutpermitting uncoupling. It will be apparent that the proper position willvary for different weights and different styles of skiing.

After'a desired position has been established, thumb screw 28 may beadjusted until it abuts the end of tube 1. Thereafter, when it isdesired to start from a rest position, tube 1 may he slid over tube 6 tolocked position until the skier reaches skiing position. He can thenslide tube 1 forwardly until further movement is stopped by thumb screw28. In this manner, the same adjustment can repeatedly be made withoutthe necessity of counting clicks as ball bearings 14 drop intosuccessive grooves 11.

Since cylindrical tube 1 is made of light weight materials, at leastsome of which are buoyant, it will float upon the water and will notdrag the end of tow rope 16 to the bottom. When the coupling parts, tube1 can readily be recovered and spool 25 be reinserted in position for anew start.

The coupling is preferably connected to the tow rope just forward of thetow bar and within easy reach of the water skier. It can, however, beplaced at the boat end of the tow line, if desired, in which case theoperator facing surfaces of pads 23 are convex, and the outer faces ofspool 25 are concave. In this mannenspool 25 is held between pads 23 andmay be withdrawn only by spread- 4 of the boat must also adjust thecoupling, by the use of a slidable control, that would be attached tocylindrical tube 1. v

While I have illustrated and described a present preferred embodiment ofmy invention, it is to be understood that I do not limit myself thereto,and that my invention may be'otherwise variously practiced within thescope of the following claims.

I claim:

1. A tension coupling for release at a pre-deterni ip ed load comprisinga body member, a resilient bifurcated member having a pair of armsextending from a common single end, the exterior surfaces of the opposedends of said arms being spaced apart a distance at least equal to theinside diameter of the tubular body member, said bifurcated member beingslidably positioned within a reccss in the body member, a first tensionmember adapted to extend into the body member and connected to thesingle end of the bifurcated member, position holding means extendingbetween the body member and the first tension member and in operativerelationship between the body member and the bifurcated member wherebythe bifurcated membermay be axially positioned relative to the bodymember as desired from a non-release position in which the ends of thearms of the bifurcated member are contained within the body member toa'position capable of releasing a load at a selected load level in whichAm" idu-ln .vi 9% t c Cuuuuou sin cuu, A3 exterior s :faces of theoppmed ends of said branches being spaced apart a distance at leastequal to the inside diameter of the tubular body member, said bifurcatedmember being slidably positioned within the tubular member, a firsttension member adapted to extend into the body member and connected tothe single end of the bifurcated member, detent means on the tubularmember engageable with recesses in the first tension member andcontrollably positioning the tubular member relative to the firsttension member and the bifurcated member from. a locked position inwhich the ends of the branches of the bifurcated member are disposedwithin the tubular member to an unlocked position in which the said endsare disposed without the tubular member, a second tension member, secondtension member engaging surfaces formed upon the branches of thebifurcated member, and non-planar cooperating surfaces formed upon thesecond tension member and arranged to cooperate with said surfaces onthe branches of the bifurcated member whereby the second tension membermay be springably clamped between branches of the bifurcated member.

3. A tension coupling for releaseat a pre-determined load comprising abody member, a resilient bifurcated member slidably positioned within arecess in the body member, non-planar surfaces formed upon the ends ofthe branches of the bifurcated member, a first tension member adapted toextend into the boy member and connected to the single end of thebifurcated member, a second tension member having non-planar surfacesarranged to cooperate with the non-planar surfaces of the bifurcatedmember, whereby the second tension mem ber may be springably clampedbetween the branches of the bifurcated member, r. sent means on the bodymember engageable with recesses in the first tension member coniiollublypositioning the body member relative to the first tension member and thebifurcated member, whereby the ends of the branches or" the bifurcatedmember may be disposed from a position within the recess in the bodymember therebypreventing release of V the second tension member from itsposition between its position between said branches, and stop means ad-'justably fitted to the first tension member and disposed to contact thebody member whereby movement of the first tension member relative to thebody member is limited.

4. A tension coupling for release at a pre-dctermined member slidablypositioned within the tubular member, convex surfaces formed upon theends of the branches of the bifurcated member, a tension member adaptedto extend into the body member and connected to the single end of thebifurcnetd member, a spool member having concave end surfaces arrangedto cooperate with the convex surfaces of the bifurcated member wherebythe spool member may be embraced between the branches of the bifurcatedmember, detent means on the tubular member engageable with recesses inthe tension member controllably positioning the tubular member relativeto the tension member and bifurcated member whereby the ends of thebranches of the bifurcated member may be disposed from a position withinthe tubular member thereby preventing release of the spool member fromits position between said branches to a position without said tubularmember thereby permitting release of the spool member from its positionbetween said branches under a load, and stop means adiustably fitted tothe tension member and disposed to contact the tubular member wherebymovement of the tension member relative to the tubular member islimited.

5. A tension coupling for water skiing adapted to release a tow bar froma boat at a pre-determined load comprising a tubular body member, aresilient bifurcated 1 load comprising a tubular member, a resilientbifurcated m 6 1 member slidably positioned within a bore in the tubularbody member, convex branchesv of the bifurcated me her, a tension memberadapted to extend into the tubular body member and connected at one endto the Single end of the bifurcated member and connected at the otherend to one-of the boat and tow bar, a spool member having concave endsurfaces arranged to cooperate with the convex surfaces of thebifurcated member whereby the spool member may be embraced between thebranches of the bifurcated member, said spool member being connected tothe other end of the boat and tow bar, detent means on the tubular bodymember engageable'with rew cesses in the tension membercontrollably-positioning the tubular member relative to the tensionmember and the bifurcated member whereby the ends of the branches of thebifurcated member'may be deposed from a position within the tubularmember thereby preventing release of the spool member from its positionbetween said branches to a position without said tubular member therebypermitting release of the spool member from its position between saidbranches, and stop means adjustably fitted to the tension member anddisposed to contact the tubular member whereby movement of the tensionmember relative to the tubular member is limited.

References Cited UNITED STATES PATENTS 1,409,776 3/1922 Randall 280-4501,434,931 11/1922 Tucker 280449 2,583,680 1/1952 Brennan 24-26O X2,654,135 10/ 1953 Grizzard. 3,083,992 4/1963 Pos. 3,171,183 3/1965Johnson.

BERNARD A. GELAK, Primary Examiner.

1. A TENSION COUPLING FOR RELEASE AT A PRE-DETERMINED LOAD COMPRISING ABODY MEMBER, A RESILIENT BIFURCATED MEMBER HAVING A PAIR OF ARMSEXTENDING FROM A COMMON SINGLE END, THE EXTERIOR SURFACES OF THE OPPOSEDENDS OF SAID ARMS BEING SPACED APART A DISTANCE AT LEAST EQUAL TO THEINSIDE DIAMETER OF THE TUBULAR BODY MEMBER, SAID BIFURCATED MEMBER BEINGSLIDABLY POSITIONED WITHIN A RECESS IN THE BODY MEMBER, A FIRST TENSIONMEMBER ADAPTED TO EXTEND INTO THE BODY MEMBER AND CONNECTED TO THESINGLE END OF THE BIFURCATED MEMBER, POSITION HOLDING MEANS EXTENDINGBETWEEN THE BODY MEMBER AND THE FIRST TENSION MEMBER AND IN OPERATIVERELATIONSHIP BETWEEN THE BODY MEMBER AND THE BIFURCATED MEMBER WHEREBYTHE BIFURCATED MEMBER MAY BE AXIALLY POSITIONED RELATIVE TO